Physical disability is the most prevalent major health problem of aging populations, and the associated needs for medical services are large. Yet, while longitudinal studies of risk factors for cardiovascular disease have identified major modifiable risk factors and have led to strategies for reduction of morbidity and mortality, such studies in musculoskeletal disease remain in their infancy. This 20 year longitudinal study of 961 individuals studied from an average age of 58 in 1984 and due to reach age 78 in 2004 will (1) identify risk factors for physical disability, radiologic osteoarthritis, and associated use of medical services, (2) assess changes in exercise and other risk factors in terms of cumulative lifetime disability and cumulative health care utilization over time, and (3) establish risk factor models for osteoporotic fractures. The role of physical exercise is particularly emphasized. The investigators will assess development of disability, progression of disability, and risk factor models in minority as compared with predominately white non-Hispanic populations. The investigators state that this project is enabled by extensive previous work and a unique data set. They point out that the application extends their investigations into important new questions of cumulative morbidity and costs, analysis of costs and benefits, long-term disability and cost outcomes, risk factors in minority populations, and effects of changes in risk factor status upon disability, cost, and mortality outcomes. The application proposes to continue data acquisition into the eighth and ninth decades, the age when this cohort will experience the greatest degrees of disability, decline in health, and use of health services. The investigators state that the results will suggest public policy initiatives directed at decreasing lifetime morbidity and medical care costs through preventive mechanisms which reduce modifiable risk factors. They further state that the overall project objective is to understand how improvements in exercise and other risk factor status may retard functional decline and reduce the need for medical care.